Charge control @ 60VDC?
By pvale, Section Controls Posted on Mon May 12th, 2008 at 01:24:37 AM MST
Very nice UPS may be useful

I have this nice business grade powerware UPS. A ham at our hamfest last year gave it to me because he didn't want to haul it home. It's a Powerware 9000 series 700W full time UPS with sine wave output. It will cold start with no AC line applied. It uses (5) 12V 5Ah in series for 60VDC. When I got it, the batteries were toast. I bought a new set of 12V 5Ah batteries to put in it. It came with an external battery box that had already been stripped of it's batteries. Being an online UPS and cold starting, it has a good use of being a backup power source for the wife's O2 concentrator. These batteries are all from motorized wheelchairs. There is a place in town that sells and works on scooters and wheelchairs. Most of them were pretty sulphated when I got them. Now this UPS charges it's batteries with a ringing waveform that effectively desulphated these 5 wheelchair batteries. I just bought a bunch of HF solar panels, and am thinking that I could series 5 of them and charge these batteries via solar power. The internal charger has it's own fuse, so could be disabled. Of course the panels are 15 watts apeice, so the string would be 75 watts total. I've looked all over the net, and while I can find plenty of charge controllers for all voltages up to 48V, there seems to be no small charge controllers that will work up to 60VDC nominal. It will keep the wife's O2 concentrator up for 30-45 minutes. Gives me time to set up the generator. If I could solar power the batteries, maybe I could use it for some other loads. Anyone got any ideas for controlling the solar power input to this?

Charge control @ 60VDC? | 12 comments (12 topical, 0 editorial)

Re: Charge control @ 60VDC? (3.00 / 0) (#1) by independent on Sun May 11th, 2008 at 09:19:17 PM MST (User Info)

The main thing I can think of is that 60v DC might exceed your local regulations for extra low voltage (household voltage is considered low voltage). If this is the case it might be illegal, depending on your location, to wire this up yourself. The obvious downside might be not being covered by your insurance should an accident happen. From what I know the highest voltage used in RE is 48v.

Re: Charge control @ 60VDC? (3.00 / 0) (#2) by independent on Sun May 11th, 2008 at 10:06:37 PM MST (User Info)

I mean highest commonly used RE voltage is 48v dc [ Parent ]

Re: Charge control @ 60VDC? (3.00 / 0) (#3) by Opera House on Mon May 12th, 2008 at 06:20:29 AM MST (User Info)

I'd grab another discarded UPS and convert it to a voltage doubler and use two Harbor freight panels.  No use spending all that money on panels when you are limited in what you can charge these 5AH batteries at.

Re: Charge control @ 60VDC? (3.00 / 0) (#4) by Old F on Mon May 12th, 2008 at 07:09:06 AM MST (User Info) http://www.oldf.homestead.com

Pvale What hamfest  was it ? You mite be better off selling it at this years hamfest seeing you got it working. An use the money toward a new 12 volt inverter an a charge controller . This would give you more flexibility to add on   to you system later. 60 volts is an odd duck  an you would have to  do some  home brew to get going. An if the inverter goes out you could have a hard time replacing it. Old F [ Parent ]

Re: Charge control @ 60VDC? (3.00 / 0) (#6) by veewee77 on Mon May 12th, 2008 at 09:18:38 AM MST (User Info)

volts would be ok. . . But, if you are going to be running mostly AC Line-level devices and equipment, you would be far better off in the long run to start at 48V from the get-go instead of having to upgrade later. V systems require very heavy wiring on the 12V side and copper is not cheap these days. 48V systems don't require such heavy wire, so the wiring will be cheaper. The 48V equipment usually has better features and in some cases may even be less expensive than the 12V equipment, and in many cases is more efficient. If you are intending to go off-grid anytime, you'll be money ahead starting out at 48V on your system. As far as that UPS goes, I would just use it as it is for backup power, which is what it is designed to do. If the power fails, it will carry small, required loads for a time. I wouldn't permanently wire it into your house because that opens up a complete new can of worms. Using it as it is is already approved. Connecting solar panels to the battery to charge them as an alternative method might still be allowed, provided that thing is not permanently connected into your house. I have used several different UPSs around my place for backup power. Example, I have a 7KW Ferrups unit that runs on 48Volts and puts out 120/240VAC. It lives out in an outbuilding and I have a long extension cord that I run into the house as needed to power some things I need if the power fails. No code violations that way. . . Doug P.S. On a side note, if anyone wants that 7KW Ferrups, I'd sell it. . . [ Parent ]

Re: Charge control @ 60VDC? (3.00 / 0) (#5) by wooferhound (tim((NoSpamAt))wooferhound.com) on Mon May 12th, 2008 at 07:43:09 AM MST (User Info) http://wooferhound.com

Wouldn't 5 batteries in series need to have 72 volts for charging ? W o o f -={(

Re: Charge control @ 60VDC? (3.00 / 0) (#7) by Ungrounded Lightning Rod on Mon May 12th, 2008 at 02:56:26 PM MST (User Info)

Check to see if the batteries are floating rather than being tied to the line neutral or case. If they are, you could put your protective ground a couple batteries from one end.  Then you'd have a -24v system and a +36v system.  B-)  Put the batteries in separate boxes and only bring the two "halves" together at the inverter - at a covered connector. Limit for "low voltage" is typically 50v nominal.  This is because that's about as high as you can go before you start getting a grab-and-get-stuck-to-it electrocution hazard. I suspect it's actually 50v because Bell figured that out and standardized on 48V (to minimize copper usage within the constraint of not electrocuting their workers), then the codes were written taking the phone company's usage into account.  B-)

Re: Charge control @ 60VDC? (3.00 / 0) (#8) by ghurd on Mon May 12th, 2008 at 03:46:39 PM MST (User Info)

Hey ULR, um... CRAP! About that whole "have a -24v system and a +36v thing". Timely smack in the face. (mine) Thanks, G- [ Parent ]

Re: Charge control @ 60VDC? (3.00 / 0) (#9) by Opera House on Tue May 13th, 2008 at 07:37:58 AM MST (User Info)

Picture clearly shows 5 batteries in series.  It is just not that hard to boost voltage up to 60-72 volts from any 24V or higher source.  Especially  when AH batteries would limit the current to less than an amp.  No need to worry about code when wiring is internal to cabinet.  I'd take it in a heartbeat. [ Parent ]

Re: Charge control @ 60VDC? (3.00 / 0) (#10) by Tritium on Tue May 13th, 2008 at 10:52:56 AM MST (User Info)

I have the same brand but mine supplies 15A at 120vac. I run mine from external batteries from an old apc battery pack. These units have a molex style connector at the back for external battery packs. Thurmond

Re: Charge control @ 60VDC? (3.00 / 0) (#11) by pvale (pvale at pvale dot com) on Tue May 13th, 2008 at 10:55:42 AM MST (User Info)

Those batteries that are sitting on the shelf below the unit are external batteries. They are 12Ah batteries from wheelchairs. They were too big to fit inside the external battery case. There are also (5) 5Ah batteries inside the unit shown in the first picture. Opera; I am curious how I may boost 48 volts easily to this level. I probably would have to chop the 48 volts, transform it up to what I need, and rectify it. Right? Most of the invertors that people use do this to bring the incoming DC up to a level that will make the peak value of the output waveform. As said by someone earlier, it is probably not worth messing with this UPS to make it generally useful in a RE system. I will probably keep it like it is, as a backup power supply to keep wifey's O2 concentrator running long enough for me to get generator running. I have other MSW inverters that I use commonly for other things.

Re: Charge control @ 60VDC? (3.00 / 0) (#12) by Bruce S (bruce(dot)stahl <at>gmail (dot)(com)) on Fri May 16th, 2008 at 09:59:31 AM MST (User Info)

Couple other things to think about. If this is a true sine wave output. then I would keep it. Your wife's concentrator, is it pneumatic? or pump? if it's pump then it would be a very good idea to keep this. Those pumps don't play well with MSW boxes for very long without a running cap along with it. Since you have the HF panels, you could a couple different ways. 1.)Tie 5 in series and attach them directly to the batteries, with 15 watts input your not likely to over charge them for a long time. These normally reach above the 12V each that they are supposed to be for but will quickly drop once loaded. 2.) Tie them together into a 12V array and use a voltage multiplier circuit to get it up to charging voltage. the current will still be low enough to not have to worry too much about overcharging. NOTE: just make sure the diodes and caps for the multiplier is above the voltage of the output i.e. up around 100V for the caps and 24V minimum rating for diodes would be a good safe level. Hope this helps Bruce S

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